Cadr

CADR, or Clean Air Delivery Rate, is a standardized metric used to quantify the performance of room air purifiers in removing airborne particulates. It is expressed in cubic feet per minute (CFM) and reflects the amount of clean air a purifier delivers to a room per unit of time.

The CADR rating is defined by the Association of Home Appliance Manufacturers (AHAM) through its Verifide program. In testing, units are placed in a controlled chamber with known concentrations of test aerosols and the purifier’s effectiveness in reducing those concentrations is measured. Ratings are provided for three particle-size categories—smoke, dust, and pollen—to represent small, medium, and large particles. The values indicate the cubic feet per minute of clean air the purifier can deliver for each category when operated at a specified speed.

Interpretation and limits: A higher CADR means faster removal of that particle type. Purifiers certified by AHAM display a CADR alongside the model and are designed to facilitate comparison between products. CADR depends on the unit’s setting and can vary widely across models.

Limitations: CADR measures particulate removal only and does not account for gases, odors, or volatile organic compounds. Some purifiers with carbon filters address gases, but CADR ratings may not reflect this performance. Real-world results depend on room size, air mixing, placement, and filter condition. CADR is a useful comparative metric but should be considered with room size and the manufacturer’s recommended coverage.